Display panel, driver circuit, driving method, and electronic apparatus

ABSTRACT

A display panel includes: display elements; a plurality of drive electrodes; one or more touch detecting electrodes that form a capacitor along with the corresponding drive electrode; a main driver unit that generates a basic drive signal including a pulse part supplied to the drive electrodes; and a first auxiliary driver unit that includes a capacitive element and that exchanges electric charges between the capacitive element and the drive electrodes in synchronization with the pulse part.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/718,634, filed Dec. 18, 2012, which claims priority toJapanese Priority Patent Application JP 2012-010743 filed in the JapanPatent Office on Jan. 23, 2012, the entire content of which is herebyincorporated by reference.

BACKGROUND

The present disclosure relates to a display panel having a function ofdetecting a touch of an external adjacent object, a driver circuit and adriving method used in such a display panel, and an electronic apparatushaving such a display panel.

Recently, a display panel which allows an input of information insteadof using normal mechanical buttons by mounting a touch detecting devicecalled a touch panel on a display panel such as a liquid crystal displaypanel or incorporating a touch panel and a display panel into a body anddisplaying various button images on the display panel has attractedattention. Such a display panel having a touch detecting function doesnot employ an input device such as a keyboard, a mouse, and a keypad andthus has been increasingly used for portable information terminals suchas mobile phones in addition to computers.

Touch panels are classified into several types such as an optical type,a resistance type, and a capacitance type. For example, JP-T-2006-511879proposes a capacitance type touch panel in which plural electrodesextending in a direction are arranged to cross each other. In the touchpanel, the electrodes are connected to a control circuit and aresupplied with an excitation current from the control circuit to detectan external adjacent object.

For example, JP-A-2009-258182 proposes a so-called in-cell display panelin which a common electrode for display originally disposed in a displaypanel is used together as one electrode of a pair of touch-sensorelectrodes and the other electrode (touch detecting electrode) isarranged to cross the common electrode. Several kinds of so-calledon-cell display panels in which a touch panel is formed on a displaysurface of a display panel have been proposed.

SUMMARY

However, recently, increases in precision or size of a display panelhave progressed. For example, when a display panel and a touch panel aremade to operate in synchronization with each other, the ratio of thewriting period of a pixel signal in one frame period increases with anincrease in the number of horizontal lines and thus the time to detect atouch is shortened. Accordingly, it is necessary for the touch panel toperform a touch detecting operation for a short time while maintainingtouch detection accuracy which is the original objective.

It is therefore desirable to provide a display panel, a driver circuit,a driving method, and an electronic apparatus, which can detect a touchfor a short time while suppressing a decrease in touch detectionaccuracy.

An embodiment of the present disclosure is directed to a display panelincluding display elements, plural drive electrodes, one or more touchdetecting electrodes, a main driver unit, and a first auxiliary driverunit. The one or more touch detecting electrodes form a capacitor alongwith the corresponding drive electrode. The main driver unit generates abasic drive signal including a pulse part supplied to the driveelectrodes. The first auxiliary driver unit includes a capacitiveelement and exchanges electric charges between the capacitive elementand the drive electrodes in synchronization with the pulse part.

Another embodiment of the present disclosure is directed to a drivercircuit including a capacitive element and causing electric charges tobe exchanged between the capacitive element and a drive electrode insynchronization with a pulse part, which is supplied to the driveelectrode, of a basic drive signal.

Still another embodiment of the present disclosure is directed to adriving method including supplying a pulse part of a basic drive signalto a drive electrode, and exchanging electric charges between acapacitive element and the drive electrode in synchronization with thepulse part.

Yet another embodiment of the present disclosure is directed to anelectronic apparatus including the above-mentioned display panel andexamples thereof include a television set, a digital camera, a personalcomputer, a video camera, and a portable terminal such as a mobilephone.

In the display panel, the driver circuit, the driving method, and theelectronic apparatus according to the embodiments of the presentdisclosure, the pulse part of the basic drive signal is applied to theplural drive electrodes and the pulse part is transmitted to the touchdetecting electrode via the capacitor. At this time, electric chargesare exchanged between the capacitive element and the drive electrodes insynchronization with the pulse part.

In the display panel, the driver circuit, the driving method, and theelectronic apparatus according to the embodiments of the presentdisclosure, since electric charges are exchanged between the capacitiveelement and the drive electrodes in synchronization with a pulse part,it is possible to detect a touch for a short time while suppressing adecrease in touch detection accuracy.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B are diagrams illustrating the fundamental principle of atouch detection system in a display panel according to an embodiment ofthe present disclosure and shows a state where a finger does not touchnor approach the display panel;

FIGS. 2A and 2B are diagrams illustrating the fundamental principle ofthe touch detection system in the display panel according to theembodiment of the present disclosure and shows a state where a fingertouches or approaches the display panel;

FIGS. 3A and 3B are diagrams illustrating the fundamental principle ofthe touch detection system in the display panel according to theembodiment of the present disclosure and shows examples of waveforms ofa drive signal and a touch detection signal;

FIG. 4 is a block diagram illustrating a configuration example of adisplay panel according to a first embodiment of the present disclosure;

FIG. 5 is a block diagram illustrating a configuration example of aselection switch unit shown in FIG. 4;

FIG. 6 is a cross-sectional view illustrating a schematic sectionalstructure of a display device with a touch detecting function shown inFIG. 4;

FIG. 7 is a circuit diagram illustrating a pixel arrangement in a liquidcrystal display device shown in FIG. 4;

FIG. 8 is a perspective view illustrating configuration examples of adrive electrode and a touch detection electrode in a touch detectingdevice shown in FIG. 4;

FIGS. 9A to 9C are schematic diagrams illustrating an operationalexample of a touch detection scanning operation in the display panelshown in FIG. 4;

FIG. 10 is a schematic diagram illustrating an operational example of adisplay scanning operation and a touch detection scanning operation inthe display panel shown in FIG. 4;

FIG. 11 is a block diagram illustrating a configuration example of adrive electrode scanning unit shown in FIG. 4;

FIG. 12 is a schematic diagram illustrating a mounting example of thedisplay panel shown in FIG. 4;

FIG. 13 is a circuit diagram illustrating a configuration example of anauxiliary driver unit shown in FIG. 4;

FIG. 14 is a cross-sectional view illustrating a configuration exampleof a capacitive element shown in FIG. 13;

FIGS. 15A to 15I are timing waveform diagrams illustrating anoperational example of the display panel shown in FIG. 4;

FIGS. 16A to 16F are timing waveform diagrams illustrating an example ofa touch detecting operation in the display panel shown in FIG. 4;

FIGS. 17A to 17G are timing waveform diagrams illustrating anoperational example of an auxiliary driver unit shown in FIG. 13;

FIG. 18 is a characteristic diagram illustrating a characteristicexample of the auxiliary driver unit shown in FIG. 13;

FIGS. 19A and 19B are cross-sectional views illustrating a configurationexample of a capacitive element according to a modified example of thefirst embodiment;

FIGS. 20A to 20G are timing waveform diagrams illustrating anoperational example of an auxiliary driver unit according to a modifiedexample of the first embodiment;

FIG. 21 is a block diagram illustrating a configuration example of adisplay panel according to second and third embodiments of the presentdisclosure;

FIG. 22 is a circuit diagram illustrating a configuration example of anauxiliary driver unit according to the second embodiment;

FIGS. 23A to 23G are timing waveform diagrams illustrating anoperational example of the auxiliary driver unit shown in FIG. 22;

FIG. 24 is a circuit diagram illustrating a configuration example of anauxiliary driver unit according to the third embodiment;

FIGS. 25A to 25G are timing waveform diagrams illustrating anoperational example of the auxiliary driver unit shown in FIG. 24;

FIG. 26 is a perspective view illustrating the outer configuration of atelevision set to which the display panel according to the embodimentsis applied;

FIG. 27 is a block diagram illustrating a configuration example of adisplay panel according to a modified example;

FIG. 28 is a circuit diagram illustrating a configuration example of anauxiliary driver unit shown in FIG. 27;

FIGS. 29A to 29G are timing waveform diagrams illustrating anoperational example of the auxiliary driver unit shown in FIG. 28; and

FIG. 30 is a cross-sectional view illustrating a schematic sectionalstructure of a display device with a touch detecting function accordingto a modified example.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. The description maybe made in the following order.

1. Fundamental Principle of Capacitance Type Touch Detection

2. First Embodiment

3. Second Embodiment

4. Third Embodiment

5. Application Examples

1. Fundamental Principle of Capacitance Type Touch Detection

First, the fundamental principle of touch detection in a display panelaccording to an embodiment of the present disclosure will be describedwith reference to FIGS. 1A to 3B. This touch detection system isembodied as a capacitance type touch sensor and a capacitive element isconstructed using a pair of electrodes (a drive electrode E1 and a touchdetecting electrode E2) disposed to face each other with a dielectric Dinterposed therebetween, for example, as shown in FIG. 1A. Thisstructure is expressed by an equivalent circuit shown in FIG. 1B. Thedrive electrode E1, the touch detecting electrode E2, and the dielectricD constitute a capacitive element C1. One end of the capacitive elementC1 is connected to an AC signal source (a drive signal source) S, andthe other end P thereof is grounded via a resistor R and is connected toa voltage detector (a touch detecting circuit) DET. When an ACrectangular wave Sg (FIG. 3B) of a predetermined frequency (for example,several kHz to several tens of kHz) is applied to the drive electrode E1(one end of the capacitive element C1) from the AC signal source S, anoutput waveform (a touch detection signal Vdet) appears at the touchdetecting electrode E2 (the other end P of the capacitive element C1),as shown in FIG. 3A.

In a state where a finger does not touch (or approach) the capacitiveelement, as shown in FIGS. 1A and 1B, a current I0 flows based on thecapacitance value of the capacitive element C1 with charging anddischarging of the capacitive element C1. The potential waveform of theother end P of the capacitive element C1 at this time is the same as thewaveform V0 shown, for example, in FIG. 3A and is detected by thevoltage detector DET.

On the other hand, in a state where a finger touches (or approaches) thecapacitive element, as shown in FIGS. 2A and 2B, a capacitive element C2formed by the finger is added in series to the capacitive element C1. Inthis state, currents I1 and I2 flow with the charging and discharging ofthe capacitive elements C1 and C2. The potential waveform of the otherend P of the capacitive element C1 at this time is the same as thewaveform V1 shown, for example, in FIG. 3A and is detected by thevoltage detector DET. At this time, the potential of the point P is apartial potential determined by the values of currents I1 and I2 flowingin the capacitive elements C1 and C2. Accordingly, the waveform V1 has avalue smaller than that of the waveform V0 in the non-touched state. Thevoltage detector DET compares the detected voltage with a predeterminedthreshold voltage Vth, determines that it is in a non-touched state whenthe detected voltage is higher than or equal to the threshold voltage,and determines that it is in a touched state when the detected voltageis less than the threshold voltage. In this way, it is possible todetect a touch.

2. First Embodiment Configuration Example Overall Configuration

FIG. 4 is a diagram illustrating a configuration example of a displaypanel according to a first embodiment. This display panel 1 is aso-called in-cell display panel in which a liquid crystal display deviceand a capacitance type touch detecting device are incorporated into abody.

The display panel 1 includes a control unit 11, a gate driver 12, asource driver 13, a selection switch unit 14, a drive signal generatingunit 15, a drive electrode scanning unit 16, an auxiliary driver unit18, a display device with a touch detecting function 10, and a touchdetecting unit 40.

The control unit 11 is a circuit that supplies a control signal to thegate driver 12, the source driver 13, the drive signal generating unit15, the drive electrode scanning unit 16, the auxiliary driver unit 18,and the touch detecting unit 40 on the basis of an image signal Vdispand controls the units to operate in synchronization with each other.

The gate driver 12 has a function of sequentially selecting onehorizontal line which is a target of a display driving operation of thedisplay device with a touch detecting function 10 on the basis of thecontrol signal supplied from the control unit 11. Specifically, the gatedriver 12 generates a scanning signal Vscan on the basis of the controlsignal supplied from the control unit 11 and supplies the scanningsignal Vscan to the gates of TFT elements Tr of pixels Pix via scanningsignal lines GCL, whereby one line (one horizontal line) of pixels Pixwhich are formed in a matrix on the liquid crystal display device 20 ofthe display device with a touch detecting function 10 is sequentiallyselected as a display driving target.

The source driver 13 serves to generate and output a pixel signal Vsigon the basis of an image signal and a source driver control signalsupplied from the control unit 11. Specifically, as described later, thesource driver 13 generates pixel signals Vsig, which are obtained bymultiplexing pixel signals Vpix of plural (three in this example) subpixels SPix of the liquid crystal display device 20 of the displaydevice with a touch detecting function 10 in a time-divisional manner,from the image signal corresponding to one horizontal line and suppliesthe generated pixel signals to the selection switch unit 14. The sourcedriver 13 also has a function of generating switch control signals Vsel(VselR, VselG, and VselB) necessary for separating the pixel signalsVpix multiplexed into the pixel signals Vsig and supplying the generatedswitch control signals to the selection switch unit 14 along with thepixel signals Vsig. This multiplexing is carried out to reduce thenumber of lines between the source driver 13 and the selection switchunit 14.

The selection switch unit 14 separates the pixel signals Vpix, which aremultiplexed into the pixel signals Vsig on the basis of the pixelsignals Vsig and the switch control signal Vsel supplied from the sourcedriver 13, and supplies the separated pixel signals to the liquidcrystal display device 20 of the display device with a touch detectingfunction 10.

FIG. 5 shows a configuration example of the selection switch unit 14.The selection switch unit 14 includes plural switch groups 17. In thisexample, each switch group 17 includes three switches SWR, SWG, and SWB.An end of each of the switches is connected and is supplied with thepixel signal Vsig from the source driver 13, and the other ends thereofare connected to the three sub pixels SPix (R, G, and B) of a pixel Pixvia a pixel signal line SGL of the liquid crystal display device 20 ofthe display device with a touch detecting function 10. ON and OFF statesof the three switches SWR, SWG, and SWB are controlled by the switchcontrol signals Vsel (VselR, VselG, and VselB) supplied from the sourcedriver 13. According to this configuration, the selection switch unit 14serves to separate the pixel signals Vpix (VpixR, VpixG, and VpixB) fromthe multiplexed pixel signal Vsig by sequentially turning on the threeswitches SWR, SWG, and SWB in a time-divisional manner in response tothe switch control signals Vsel. The selection switch unit 14 suppliesthe pixel signals Vpix to the three sub pixels SPix.

The drive signal generating unit 15 generates a DC drive signal VcomDCand an AC drive signal VcomAC and supplied the generated drive signalsto the drive electrode scanning unit 16. In this example, the DC drivesignal VcomDC is a DC signal with a voltage of 0 V. The AC drive signalVcomAC is a signal including two pulses Pt and Pi with a low-levelvoltage of 0 V and a high-level voltage of VH. As described later, thepulse Pt is supplied to the drive electrodes COML and the pulse Pi isused to initialize the auxiliary driver unit 18.

The drive electrode scanning unit 16 is a circuit that selects one ofthe DC drive signal VcomDC and the AC drive signal VcomAC supplied fromthe drive signal generating unit 15 on the basis of the control signalsupplied from the control unit 11 and that supplies the selected drivesignal as a drive signal Vcom to the drive electrodes COML (to bedescribed later) of the display device with a touch detecting function10. Specifically, the drive electrode scanning unit 16 supplies the DCdrive signal VcomDC to the drive electrodes COML in a display operation.In a touch detecting operation, the drive electrode scanning unit 16supplies the pulse Pt of the AC drive signal VcomAC to the driveelectrodes COML associated with the touch detecting operation andsupplies the DC drive signal VcomDC to the other drive electrodes COML.At this time, the drive electrode scanning unit 16 supplies the drivesignal Vcom to each block (drive electrode block B to be describedlater) including a predetermined number of drive electrodes COML.

The auxiliary driver unit 18 is a circuit that assists the drivingoperation of the drive signal generating unit 15 on the basis of thecontrol signals CTL (CTLH and CTLL) supplied from the control unit 11.Specifically, as described later, the auxiliary driver unit 18 assiststhe driving operation of the drive signal generating unit 15 so as toreduce the transition time (the rising time tr and the falling time tf)of the drive signal Vcom (pulse Pt) supplied to the drive electrodesCOML via the drive electrode scanning unit 16.

The display device with a touch detecting function 10 is a displaydevice having a touch detecting function. The display device with atouch detecting function 10 includes a liquid crystal display device 20and the touch detecting device 30. The liquid crystal display device 20is a device that sequentially scans each horizontal line and performs adisplay operation on the basis of the scanning signal Vscan suppliedfrom the gate driver 12 as described later. The touch detecting device30 serves to operate on the basis of the fundamental principle of acapacitance type touch detection and to output a touch detection signalVdet. As described later, the touch detecting device 30 is sequentiallyscanned to detect a touch on the basis of the drive signal Vcom suppliedfrom the drive electrode scanning unit 16.

The touch detecting unit 40 is a circuit that checks whether a touchwith the touch detecting device 30 is present on the basis of the touchdetection control signal supplied from the control unit 11 and the touchdetection signal Vdet supplied from the touch detecting device 30 of thedisplay device with a touch detecting function 10 and that calculatesthe coordinates of a touch in the touch detection area. The touchdetecting unit 40 includes an LPF (Low-Pass Filter) unit 42, an A/Dconversion unit 43, a signal processing unit 44, a coordinate extractingunit 45, and a detection time control unit 46. The LPF unit 42 is alow-pass analog filter that removes a high-frequency component (noisecomponent) included in the touch detection signal Vdet supplied from thetouch detecting device 30 and extracts and outputs a touch component. Aresistor R giving a DC potential (for example, 0 V) is connected betweenthe input terminals of the LPF unit 42 and the ground. The DC potential(0 V) may be given, for example, by providing a switch instead of theresistor R and turning on the switch at a predetermined time. The A/Dconversion unit 43 is a circuit that samples an analog signal outputfrom the LPF unit 42 and converts the sampled analog signal into adigital signal in synchronization with the pulse Pt of the AC drivesignal VcomAC. The signal processing unit 44 is a logic circuit thatdetects a touch with the touch detecting device 30 on the basis of theoutput signal of the A/D conversion unit 43. The coordinate extractingunit 45 is a logic circuit that calculates the coordinates on the touchpanel when a touch is detected by the signal processing unit 44. Thedetection time control unit 46 controls such circuits to operate insynchronization with each other.

(Display Device with Touch Detecting Function 10)

A configuration example of the display device with a touch detectingfunction 10 will be described in detail below.

FIG. 6 shows an example of a cross-sectional structure of a part of thedisplay device with a touch detecting function 10. The display devicewith a touch detecting function 10 includes a pixel substrate 2, acounter substrate 3 disposed to face the pixel substrate 2, and a liquidcrystal layer 6 interposed between the pixel substrate 2 and the countersubstrate 3.

The pixel substrate 2 includes a TFT substrate 21 as a circuit board,drive electrodes COML, and pixel electrodes 22. The TFT substrate 21serves as a circuit board in which various electrodes orinterconnections (such as pixel signal lines SGL or scanning signallines GCL to be described later), thin film transistors (TFT), and thelike are formed. The TFT substrate 21 is formed of, for example, glass.The drive electrodes COML are formed on the TFT substrate 21. The driveelectrodes COML are electrodes used to supply a common voltage to pluralpixels Pix (to be described later). The drive electrodes COML serve as acommon drive electrode for a liquid crystal display operation and alsoserve as a drive electrode for a touch detecting operation. Aninsulating layer 23 is formed on the drive electrodes COML and the pixelelectrodes 22 are formed thereon. The pixel electrodes 22 are electrodesused to supply a pixel signal for a display and have transparency. Thedrive electrodes COML and the pixel electrodes 22 are formed of, forexample, ITO (Indium Tin Oxide).

The counter substrate 3 includes a glass substrate 31, a color filter32, and a touch detecting electrode TDL. The color filter 32 is formedon one surface of the glass substrate 31. In the color filter 32,three-color color filter layers of red (R), green (G), and blue (B) areperiodically arranged and three colors of R, G, and B as a setcorrespond to each display pixel. The touch detecting electrode TDL isformed on the other surface of the glass substrate 31. The touchdetecting electrode TDL is an electrode that is formed of, for example,ITO and that has transparency. A polarizing film 35 is formed on thetouch detecting electrode TDL.

The liquid crystal layer 6 serves as a display functional layer andserves to modulate light passing through the liquid crystal layerdepending on an electric field state. This electric field is formed by apotential difference between the voltage of the drive electrodes COMLand the voltage of the pixel electrodes 22. A liquid crystal of atransverse electric field mode such as an FFS (Fringe Field Switching)or an IPS (In-Plane Switching) is used for the liquid crystal layer 6.

An alignment film is disposed between the liquid crystal layer 6 and thepixel substrate 2 and between the liquid crystal layer 6 and the countersubstrate 3 and an incidence-side polarizing film is disposed on thebottom surface of the pixel substrate 2, which are not shown therein.

FIG. 7 shows a configuration example of a pixel structure in the liquidcrystal display device 20. The liquid crystal display device 20 includesplural pixels Pix which are arranged in a matrix. Each pixel Pixincludes three sub pixels SPix. The three sub pixels SPix are arrangedto correspond to three colors (R, G, and B) of the color filters 32shown in FIG. 6. Each sub pixel SPix includes a TFT element Tr and aliquid crystal element LC. The TFT element Tr is formed of a thin filmtransistor and is formed of an N-channel MOS (Metal Oxide Semiconductor)TFT in this example. The source of the TFT element Tr is connected tothe pixel signal line SGL, the gate thereof is connected to the scanningsignal line GCL, and the drain thereof is connected to an end of theliquid crystal element LC. An end of the liquid crystal element LC isconnected to the drain of the TFT element Tr and the other end thereofis connected to the drive electrode COML.

The sub pixel SPix is connected to the other sub pixels SPix belongingto the same row of the liquid crystal display device 20 via a scanningsignal line GCL. The scanning signal line GCL is connected to the gatedriver 12 and is supplied with a scanning signal Vscan from the gatedriver 12. The sub pixel SPix is connected to the other sub pixels SPixbelonging to the same column of the liquid crystal display device 20 viaa pixel signal line SGL. The pixel signal line SGL is connected to theselection switch unit 14 and is supplied with a pixel signal Vpix fromthe selection switch unit 14.

The sub pixel SPix is connected to the other sub pixels SPix belongingto the same row of the liquid crystal display device 20 via a driveelectrode COML. The drive electrode COML is connected to the driveelectrode scanning unit 16 and is supplied with a drive signal Vcom fromthe drive electrode scanning unit 16.

According to this configuration, in the liquid crystal display device20, one horizontal line is sequentially selected by driving the gatedriver 12 to line-sequentially scan the scanning signal lines GCL in atime-divisional manner, and a display operation is performed for eachhorizontal line by causing the source driver 13 and the selection switchunit 14 to supply the pixel signals Vpix to the pixels Pix belonging tothe selected horizontal line.

FIG. 8 is a perspective view illustrating a configuration example of thetouch detecting device 30. The touch detecting device 30 includes thedrive electrodes COML formed on the pixel substrate 2 and the touchdetecting electrodes TDL formed on the counter substrate 3. Each driveelectrode COML has a striped electrode pattern extending in thehorizontal direction of the drawing. When performing a touch detectingoperation, as described later, a drive signal Vcom (pulse Pt) issequentially supplied to the electrode patterns for every block (driveelectrode block B to be described later) including a predeterminednumber of drive electrodes COML to perform a sequential scanning drivingoperation in a time-divisional manner. Each touch detecting electrodeTDL has a striped electrode pattern extending in the directionperpendicular to the extending direction of the electrode patterns ofthe drive electrodes COML. The electrode patterns of the touch detectingelectrode TDL are connected to the inputs of the LPF unit 42 of thetouch detecting unit 40. The electrode patterns in which the driveelectrodes COML and the touch detecting electrodes TDL intersect eachother form capacitors at the intersections.

According to this configuration, in the touch detecting device 30, atouch detection signal Vdet is output from the touch detectingelectrodes TDL to detect a touch by causing the drive electrode scanningunit 16 to supply a drive signal Vcom to the drive electrodes COML. Thatis, the drive electrodes COML correspond to the drive electrode E1 inthe fundamental principle of touch detection shown in FIGS. 1A to 3B,the touch detecting electrodes TDL correspond to the touch detectingelectrode E2, and the touch detecting device 30 detects a touch on thebasis of the fundamental principle. As shown in FIG. 8, the electrodepatterns intersecting each other from the capacitance type touch sensorin a matrix shape. Accordingly, by scanning the overall touch detectionplane of the touch detecting device 30, it is also possible to detect aposition of an approach or a contact of an external adjacent object.

The drive electrode scanning unit 16 drives the drive electrodes COMLfor each block (drive electrode block B) including a predeterminednumber of drive electrodes COML to perform a touch detection scanningoperation.

FIGS. 9A to 9C schematically illustrate a touch detection scanningoperation. In FIGS. 9A to 9C, an operation of supplying a drive signalVcom to the drive electrode blocks B1 to B20 is shown when the touchdetection plane includes 20 drive electrode blocks B1 to B20. In FIGS.9A to 9C, the hatched drive electrode block B indicates that the pulsePt of the AC drive signal VcomAC is supplied thereto and the other driveelectrode blocks B indicate that the DC drive signal VcomDC is suppliedthereto. In this example, the number of drive electrode blocks B is 20for the purpose of convenience of explanation, but is not limited tothis number.

The drive electrode scanning unit 16 supplies the drive signal Vcom tothe drive electrodes COML for each drive electrode block B. Each driveelectrode block B is set to a width (for example, about 5 mm)corresponding to the size of a user's finger. The drive electrodescanning unit 16 sequentially selects the drive electrode blocks B as atarget of the touch detecting operation and supplies the pulse Pt to thedrive electrodes COML belonging to the selected drive electrode block B,whereby all the drive electrode blocks B are scanned, as shown in FIGS.9A to 9C.

FIG. 10 schematically illustrates a display scanning operation and atouch detection scanning operation. In the display panel 1, the gatedriver 12 performs a display scanning Scand by line-sequentiallyscanning the scanning signal lines GCL in a time-divisional manner, andthe drive electrode scanning unit 16 performs a touch detection scanningScant by sequentially selecting and driving the drive electrode blocksB. In this example, the touch detection scanning Scant is performed atdouble the scanning speed of the display scanning Scand. In this way, inthe display panel 1, since the scanning speed of the touch detectionscanning is set to be higher than that of the display scanning, it ispossible to rapidly respond to a touch of an external adjacent objectand thus to improve the response characteristic to a touch detection.The scanning speed is not limited to this example, but the touchdetection scanning Scant may be performed at a scanning speed which istwo or more times the scanning speed of the display scanning Scand ormay be performed at a scanning speed which is two or less times thescanning speed of the display scanning Scand.

(Drive Electrode Scanning Unit 16)

FIG. 11 shows a configuration example of the drive electrode scanningunit 16. The drive electrode scanning unit 16 includes a scanningcontrol unit 51, a touch detection scanning unit 52, and a driver unit530. The driver unit 530 includes 20 driver units 53(1) to 53(20).Hereinafter, when it is intended to mention any one of 20 driver units53(1) to 53(20), the driver unit 53 is simply described.

The scanning control unit 51 supplies a control signal to the touchdetection scanning unit 52 on the basis of the control signal suppliedfrom the control unit 11. The scanning control unit 51 also has afunction of supplying a Vcom selection signal VCOMSEL, which indicateswhich of the DC drive signal VcomDC and the AC drive signal VcomAC tosupply to the drive electrodes COML, to the driver unit 530.

The touch detection scanning unit 52 includes a shift register andgenerates a scanning signal St for selecting the drive electrode block Bto which the pulse Pt of the AC drive signal VcomAC should be applied.Specifically, the touch detection scanning unit 52 generates pluralscanning signals St corresponding to the drive electrode blocks B on thebasis of the control signal supplied from the scanning control unit 51as described later. When the touch detection scanning unit 52 supplies,for example, a high-level signal as a k-th scanning signal St(k) to thek-th driver unit 53(k), the driver unit 53(k) supplies the pulse Pt ofthe AC drive signal VcomAC to the plural drive electrodes COML belongingto the k-th drive electrode block B(k).

The driver unit 530 selects one of the DC drive signal VcomDC and the ACdrive signal VcomAC supplied from the drive signal generating unit 15 onthe basis of the scanning signals St supplied from the touch detectionscanning unit 52 and the Vcom selection signal VCOMSEL supplied from thescanning control unit 51 and supplies the selected drive signal as thedrive signal Vcom to the drive electrodes COML. The driver unit 53 isprovided for each output signal of the touch detection scanning unit 52and supplies the drive signal Vcom to the corresponding drive electrodeblock B.

The driver unit 53 includes a logical product circuit 54, an inverter55, buffers 56 and 57, and switches SW1 and SW2. The logical productcircuit 54 generates and outputs a logical product (AND) of the scanningsignal St supplied from the touch detection scanning unit 52 and theVcom selection signal VCOMSEL supplied from the scanning control unit51. The inverter 55 generates and outputs the inverted logic of theoutput signal of the logical product circuit 54. The buffer 56 has afunction of amplifying a signal supplied from the logical productcircuit 54 to an amplitude level which can control the ON and OFF statesof the switch SW1. The ON and OFF states of the switch SW1 arecontrolled on the basis of the signal supplied from the buffer 56, oneend thereof is supplied with the AC drive signal VcomAC, and the otherend thereof is connected to plural drive electrodes COML belonging tothe drive electrode block B. The buffer 57 has a function of amplifyinga signal supplied from the inverter 55 to an amplitude level which cancontrol the ON and OFF states of the switch SW2. The On and OFF statesof the switch SW2 are controlled on the basis of the signal suppliedfrom the buffer 57, one end thereof is supplied with the DC drive signalVcomDC, and the other end thereof is connected to the other end of theswitch SW1.

According to this configuration, the driver unit 53 outputs the AC drivesignal VcomAC as the drive signal Vcom when the scanning signal St is ata high level and the Vcom selection signal VCOMSEL is at a high level,and outputs the DC drive signal VcomDC as the drive signal Vcom when theVcom selection signal VCOMSEL is at a low level. The driver unit 53outputs the DC drive signal VcomDC as the drive signal Vcom when thescanning signal St is at a low level. The driver unit 53 supplies thedrive signal Vcom output in this way to the plural drive electrodes COMLbelonging to the drive electrode block B corresponding to the driverunit 53.

(Auxiliary Driver Unit 18)

The arrangement of the blocks in the display panel 1 will be firstdescribed before describing the auxiliary driver unit 18.

FIG. 12 schematically illustrates a mounting example of the displaypanel 1. The control unit 11, the source driver 13, and the drive signalgenerating unit 15 are mounted as a COG (Chip On Glass) on the pixelsubstrate 2. The selection switch unit 14 is formed of TFT elements inthe vicinity of the display area Ad on the TFT substrate 21.

The gate driver 12 (12A and 12B) is formed of TFT elements on the TFTsubstrate 21. In this example, the gate driver 12 is disposed on each ofthe upper side (12A) and the lower side (12B) of the pixel substrate 2in FIG. 12 and can drive the pixels Pix (not shown) arranged in a matrixin the display area Ad from both sides.

The drive electrode scanning unit 16 (16A and 16B) is formed of TFTelements on the TFT substrate 21. In this example, the drive electrodescanning unit 16 is disposed on each of the upper side (16A) and thelower side (16B) of the pixel substrate 2 in FIG. 12, is supplied withthe DC drive signal VcomDC via a line LDC from the drive signalgenerating unit 15, and is supplied with the AC drive signal VcomAC viaa line LAC. The drive electrode scanning units 16A and 16B can drive theplural drive electrode blocks B arranged in parallel from both sides.

The auxiliary driver unit 18 (18A and 18B) is formed of TFT elements onthe TFT substrate 21. The auxiliary driver unit 18 is disposed in thevicinity of an end of the line LAC extending from the drive signalgenerating unit 15. Specifically, in this example, the auxiliary driverunit 18A is disposed in the vicinity of the end of the line LAC forsupplying the AC drive signal VcomAC to the drive electrode scanningunit 16A and the auxiliary driver unit 18B is disposed in the vicinityof the end of the line LAC for supplying the AC drive signal VcomAC tothe drive electrode scanning unit 16B.

The touch detecting unit 40 is mounted on a flexible printed circuitboard T and is connected to the plural touch detecting electrodes TDLarranged in parallel.

As shown in FIG. 12, in the display panel 1, the auxiliary driver unit18 (18A and 18B) is disposed at a position separated from the drivesignal generating unit 15. Accordingly, the auxiliary driver unit 18serves to reduce the transition time (the rising time tr and the fallingtime tf) of the pulse Pt supplied to the block B of the drive electrodesCOML. That is, since the line LAC includes parasitic resistance or thelike and the drive electrodes COML belonging to the drive electrodeblock B supplied with the pulse Pt via the line LAC have parasiticcapacitance or the like, the transition time of the pulse Pt may beelongated in the drive electrode block B located at a position separatedfrom the drive signal generating unit 15. Particularly, this tendency ismarked in the drive electrode block B disposed at the end of the lineLAC and thus the waveform may be broken. In the display panel 1, byproviding the auxiliary driver unit 18 to the vicinity of the end of theline LAC, it is possible to reduce the transition time of the pulse Pt.

FIG. 13 shows a configuration example of the auxiliary driver unit 18.The auxiliary driver unit 18 includes capacitive elements CH and CL andswitches SWH and SWL. One end of the capacitive element CH is connectedto one end of the switch SWH and the other end thereof is grounded. TheON and OFF states of the switch SWH are controlled on the basis of thecontrol signal CTLH supplied from the control unit 11, one end thereofis connected to one end of the capacitive element CH, and the other endthereof is connected to the line LAC. One end of the capacitive elementCL is connected to one end of the switch SWL and the other end thereofis grounded. The ON and OFF states of the switch SWL are controlled onthe basis of the control signal CTLL supplied from the control unit 11,one end thereof is connected to one end of the capacitive element CL,and the other end thereof is connected to the other end of the switchSWL and the line LAC.

According to this configuration, in the auxiliary driver unit 18, sincethe switch SWH is changed to the ON state on the basis of the controlsignal CTLH at the rising time of the pulse Pt of the AC drive signalVcomAC, electric charges are exchanged between the capacitive element CHand the drive electrode block B as a target of the touch detectingoperation, thereby reducing the rising time tr of the pulse Pt in thecorresponding drive electrode block B. Similarly, in the auxiliarydriver unit 18, since the switch SWL is changed to the ON state on thebasis of the control signal CTLL at the falling time of the pulse Pt ofthe AC drive signal VcomAC, electric charges are exchanged between thecapacitive element CL and the drive electrode block B as a target of thetouch detecting operation, thereby reducing the falling time tf of thepulse Pt in the corresponding drive electrode block B.

The auxiliary driver unit 18 has a function of initializing the voltagesof the capacitive elements CH and CL before turning on the switches SWHand SWL using the pulse Pi of the AC drive signal VcomAC as describedlater.

A configuration example of the capacitive elements CH and CL of theauxiliary driver unit 18 will be described below. The capacitive elementCH will be described representatively below, but the same is true of thecapacitive element CL.

FIG. 14 shows an example of a partial sectional structure of thecapacitive element CH. The capacitive element CH is formed on the pixelsubstrate 2 shown in FIG. 6. The capacitive element CH includeselectrodes 61 and 62 and an insulating layer 63 interposed between theelectrodes 61 and 62. The electrode 61 is formed in the same layer asthe pixel electrodes 22 (FIG. 6) and is formed of, for example, ITO. Theelectrode 62 is formed in the same layer as the drive electrodes COML(FIG. 6) and is formed of, for example, ITO. The insulating layer 63corresponds to the insulating layer 23 (FIG. 6). The electrode 62 isconnected to the interconnection layer 65 formed on the TFT substrate 21via plural contacts CONT. The interconnection layer 65 is formed in thesame layer as the pixel signal line SGL (FIG. 7) and is formed of, forexample, aluminum. In this example, the electrode 61 (theinterconnection layer 65) is connected to one end of the switch SWH andthe electrode 62 is grounded. In the capacitive element CL, theelectrode 61 (the interconnection layer 65) is connected to one end ofthe switch SWL and the electrode 62 is grounded.

In this way, the capacitive elements CH and CL can be formed at the sametime as forming the display device with a touch detecting function 10without performing any additional manufacturing process through themanufacturing processes of the display device with a touch detectingfunction 10 shown in FIG. 6 and the like.

Here, the liquid crystal element LC corresponds to a specific example ofthe “display element” in the embodiment of the present disclosure. Thedrive signal generating unit 15 corresponds to a specific example of the“main driver unit” in the embodiment of the present disclosure. The ACdrive signal VcomAC corresponds to a specific example of the “basicdrive signal” in the embodiment of the present disclosure and the pulsePt corresponds to a specific example of the “pulse part” in theembodiment of the present disclosure. One of the capacitive element CHand switch SWH and the capacitive element CL and switch SWL correspondsto a specific example of the “first auxiliary driver unit” in theembodiment of the present disclosure and the other end thereofcorresponds to a specific example of the “second auxiliary driver unit”in the embodiment of the present disclosure.

[Operations and Advantages]

The operations and advantages of the display panel 1 according to thisembodiment will be described below.

(Overall Operations)

The overall operations of the display panel 1 will be described below inbrief with reference to FIG. 4. The control unit 11 supplies the controlsignals to the gate driver 12, the source driver 13, the drive signalgenerating unit 15, the drive electrode scanning unit 16, the auxiliarydriver unit 18, and the touch detecting unit 40 on the basis of theimage signal Vdisp, and controls the units to operate in synchronizationwith each other.

The gate driver 12 supplies the scanning signal Vscan to the liquidcrystal display device 20 and sequentially selects one horizontal lineas a target of a display driving operation. The source driver 13generates a pixel signal Vsig into which the pixel signal Vpix ismultiplexed and a switch control signal Vsel corresponding thereto andsupplies the generated signals to the selection switch unit 14. Theselection switch unit 14 separates the pixel signal Vpix on the basis ofthe pixel signal Vsig and the switch control signal Vsel and suppliesthe separated pixel signal Vpix to the sub pixels SPix constituting onehorizontal line. The drive signal generating unit 15 generates a DCdrive signal VcomDC and an AC drive signal VcomAC. The drive electrodescanning unit 16 selects one of the DC drive signal VcomDC and the ACdrive signal VcomAC and supplies the selected drive signal as the drivesignal Vcom for each drive electrode block B. The auxiliary driver unit18 assists the driving operation of the drive signal generating unit 15.The display device with a touch detecting function 10 performs the touchdetecting operation at the same time as performing the display operationand outputs the touch detection signal Vdet from the touch detectingelectrodes TDL.

The touch detecting unit 40 detects a touch on the basis of the touchdetection signal Vdet. Specifically, the LPF unit 42 removes a highfrequency component (noise component) included in the touch detectionsignal Vdet and extracts and outputs a touch component. The A/Dconversion unit 43 converts an analog signal output from the LPF unit 42into a digital signal. The signal processing unit 44 detects a touchwith the display device with a touch detecting function 10 on the basisof the output signal of the A/D conversion unit 43. The coordinateextracting unit 45 calculates the coordinates on the touch panel when atouch is detected by the signal processing unit 44. The detection timecontrol unit 46 controls the LPF unit 42, the A/D conversion unit 43,the signal processing unit 44, and the coordinate extracting unit 45 tooperate in synchronization with each other.

(Detailed Operations)

The detailed operations of the display panel 1 will be described below.

FIGS. 15A to 15I are diagrams illustrating a timing waveform of thedisplay panel 1, where FIG. 15A represents the waveform of the scanningsignal Vscan, FIG. 15B represents the waveform of the pixel signal Vsig,FIG. 15C represents the waveform of the switch control signal Vsel, FIG.15D represents the waveform of the pixel signal Vpix, FIG. 15Erepresents the waveform of the Vcom selection signal VCOMSEL, FIG. 15Frepresents the waveforms of the drive signal Vcom, and FIG. 15Grepresents the waveform of the touch detection signal Vdet.

In the display panel 1, a touch detecting operation and a displayoperation are performed in each horizontal period (1H). In the touchdetecting operation, the drive electrode scanning unit 16 performs thetouch detection scanning by sequentially supplying the pulse Pt of theAC drive signal VcomAC to the drive electrodes COML associated with thetouch detecting operation for each drive electrode block B, and thetouch detecting unit 40 detects a touch on the basis of the touchdetection signal Vdet output from the touch detecting electrodes TDL. Inthe display operation, the gate driver 12 sequentially supplies thescanning signal Vscan to the scanning signal lines GCL and the sourcedriver 13 and the selection switch unit 14 write the pixel signal Vpixto the sub pixels SPix constituting the selected horizontal line. Thedetails thereof will be described below.

First, at time t1, one horizontal period (1H) is started and thescanning control unit 51 of the drive electrode scanning unit 16 changesthe voltage of the Vcom selection signal VCOMSEL from a low level to ahigh level (FIG. 15G). Accordingly, in the k-th driver unit 53(k)associated with the touch detecting operation in the drive electrodescanning unit 16, the switch SW1 is turned on, the switch SW2 is turnedoff, the AC drive signal VcomAC (FIG. 15A) generated by the drive signalgenerating unit 15 is supplied as the drive signal Vcom(B(k)) to thedrive electrodes COML belonging to the k-th drive electrode block B(k)via the switch SW1 (FIG. 15H). In the driver units 53 other than thedriver unit 53(k), the switch SW1 is turned off, the switch SW2 isturned on, and the DC drive signal VcomDC (FIG. 15B) generated by thedrive signal generating unit 15 is supplied to the drive electrodes COMLbelonging to the corresponding drive electrode block B via the switchSW2 (FIG. 15H).

Then, the drive signal generating unit 15 generates the pulse Pt andoutputs the generated pulse as the AC drive signal VcomAC in the periodof times t2 to t3 (FIG. 15A). Accordingly, the pulse Pt also appears inthe drive signal Vcom(B(k)) supplied to the k-th drive electrode blockB(k) (FIG. 15H). The drive signal Vcom(B(k)) is transmitted to the touchdetecting electrodes TDL via an electrostatic capacitor and the touchdetection signal Vdet is changed (FIG. 15I).

The A/D conversion unit 43 of the touch detecting unit 40 converts theoutput signal of the LPF unit 42 to which the touch detection signalVdet (FIG. 15I) is input in an A/D conversion manner at the samplingtime ts. The signal processing unit 44 of the touch detecting unit 40performs the touch detecting operation on the basis of the A/Dconversion results collected in plural horizontal periods, as describedlater.

Then, the scanning control unit 51 of the drive electrode scanning unit16 changes the voltage of the Vcom selection signal VCOMSEL from a highlevel to a low level at time t4 (FIG. 15G). Accordingly, in the driverunit 53(k) of the drive electrode scanning unit 16, the switch SW1 isturned off, the switch SW2 is turned on, the DC drive signal VcomDC(FIG. 15B) generated by the drive signal generating unit 15 is suppliedas the drive signal Vcom(B(k)) to the drive electrodes COML belonging tothe corresponding drive electrode block B(k) via the switch SW2 (FIG.15H).

Thereafter, the drive signal generating unit 15 generates the pulse Piand outputs the generated pulse as the AC drive signal VcomAC (FIG.15A), until the horizontal period (1H) is ended. This pulse Pi is usedto initialize the auxiliary driver unit 18 as described below.

The gate driver 12 supplies the scanning signal Vscan to the n-thscanning signal line GCL(n) associated with the display operation attime t5 and thus the scanning signal Vscan(n) is changed from a lowlevel to a high level (FIG. 15C). Accordingly, the gate driver 12selects one horizontal line as a target of the display operation.

The source driver 13 supplies a pixel voltage VR for the red sub pixelsSPix as the pixel signal Vsig to the selection switch unit 14 (FIG.15D), and generates a switch control signal VselR which is at a highlevel in the period in which the pixel voltage VR is supplied (FIG.15E). The selection switch unit 14 separates the pixel voltage VRsupplied from the source driver 13 from the pixel signal Vsig by turningon the switch SWR in the period in which the switch control signal VselRis at a high level, and supplies the separated pixel voltage as thepixel signal VpixR to the red sub pixels SPix via the pixel signal lineSGL (FIG. 15F). Since the pixel signal line SGL is in a floating stateafter the switch SWR is turned off, the voltage of the pixel signal lineSGL is maintained (FIG. 15F).

Similarly, the source driver 13 supplies a pixel voltage VG for thegreen sub pixels Spix to the selection switch unit 14 along with thecorresponding switch control signal VselG (FIGS. 15D and 15E), and theselection switch unit 14 separates the pixel voltage VG from the pixelsignal Vsig on the basis of the switch control signal VselG and suppliesthe separated pixel voltage as the pixel signal VpixG to the green subpixels SPix via the pixel signal line SGL (FIG. 15F).

Thereafter, similarly, the source driver 13 supplies a pixel voltage VBfor the blue sub pixels Spix to the selection switch unit 14 along withthe corresponding switch control signal VselB (FIGS. 15D and 15E), andthe selection switch unit 14 separates the pixel voltage VB from thepixel signal Vsig on the basis of the switch control signal VselB andsupplies the separated pixel voltage as the pixel signal VpixB to theblue sub pixels SPix via the pixel signal line SGL (FIG. 15F).

The gate driver 12 changes the scanning signal Vscan(n) of the n-thscanning signal line GCL from a high level to a low level at time t9(FIG. 15C). Accordingly, the sub pixels Spix of one horizontal lineassociated with the display operation are electrically isolated from thepixel signal line SGL.

At time t11, one horizontal period (1H) is ended and a new horizontalperiod (1H) is started.

Thereafter, by repeating the above-mentioned operation, the displaypanel 1 performs the display operation on the overall display planethrough the line sequential scanning, and performs the touch detectingoperation on the overall touch detection plane by scanning the driveelectrodes for each drive electrode block B as described later.

FIGS. 16A to 16F show operational examples of a touch detection scanningoperation, wherein FIG. 16A represents the waveform of the AC drivesignal VcomAC, FIG. 16B represents the waveform of the DC drive signalVcomDC, FIG. 16C represents the waveform of the Vcom selection signalVCOMSEL, FIG. 16D represents the waveform of the scanning signal St,FIG. 16E represents the waveform of the drive signal Vcom, and FIG. 16Frepresents the waveform of the touch detection signal Vdet. In thedrawing, the transition time of the drive signal Vcom or the like isshown to be sufficiently small for the purpose of convenience ofexplanation.

As shown in FIGS. 16A to 16F, the drive electrode scanning unit 16performs the touch detection scanning operation by supplying the pulsePt of the AC drive signal VcomAC (FIG. 16A) to the corresponding driveelectrode block B (FIG. 16E) on the basis of the scanning signal St(FIG. 16D) generated by the touch detection scanning unit 52. At thistime, the drive electrode scanning unit 16 supplies the pulse Pt to therespective drive electrode blocks B over a predetermined number ofhorizontal periods. The touch detecting unit 40 samples the touchdetection signal Vdet based on the pulse Pt in each horizontal period,and the signal processing unit 44 detects a touch to the areacorresponding to the drive electrode block B on the basis of the pluralsampling results after the sampling, in the final horizontal period ofthe predetermined number of horizontal periods, is ended. In this way,since a touch is detected on the basis of the plural sampling results,it is possible to statically analyze the sampling results, therebysuppressing the degradation of the S/N ratio due to the differencebetween the sampling results and enhancing the touch detection accuracy.

(Detailed Operation of Auxiliary Driver Unit 18)

The operation of the auxiliary driver unit 18 will be described indetail below.

FIGS. 17A to 17G show timing waveform examples of the touch detectingoperation in the display panel 1, where FIG. 17A represents the waveformof the AC drive signal VcomAC in the output of the drive signalgenerating unit 15, FIG. 17B represents the waveform of the Vcomselection signal VCOMSEL, FIG. 17C represents the waveform of thecontrol signal CTLH, FIG. 17D represents eh waveform of the controlsignal CTLL, FIG. 17E represents the waveform of the voltage Vch of thecapacitive element CH, FIG. 17F represents the waveform of the voltageVcl of the capacitive element CL, and FIG. 17G represents the waveformof the drive signal Vcom supplied to the drive electrode block B as atarget of the touch detecting operation. Times t1 to t4 and t11 in FIGS.17A to 17G correspond to times t1 to t4 and t11 in FIGS. 15A to 15I,respectively.

In the auxiliary driver unit 18, at the rising and falling of the pulsePt of the AC drive signal VcomAC, electric charges are exchanged betweenthe capacitive elements CH and CL and the drive electrodes COMLbelonging to the drive electrode block B as a target of the touchdetecting operation. The details thereof will be described below.

First, at time t1, the scanning control unit 51 of the drive electrodescanning unit 16 changes the Vcom selection signal VCOMSEL from a lowlevel to a high level (FIG. 17B). Accordingly, in the driver unit 53associated with the touch detecting operation in the drive electrodescanning unit 16, the switch SW1 is turned on and the line LAC and thedrive electrode block B as a target of the touch detecting operation areconnected to each other.

Then, the control unit 11 changes the control signal CTLH to a highlevel in a predetermined period which is started from time t2 at whichthe pulse Pt (FIG. 17A) rises (FIG. 17C). Accordingly, the switch SWH ofthe auxiliary driver unit 18 is turned on, the electric charges movefrom the capacitive element CH to the drive electrode block B via theline LAC, and the voltage of the drive electrode block B (FIG. 17G)rises for a short time. Accordingly, the voltage Vch of the capacitiveelement CH is lowered and the level thereof is maintained up to time t6(to be described later) (FIG. 17E).

The control unit 11 changes the control signal CTLL to a high level in apredetermined period which is started from time t3 at which the pulse Pt(FIG. 17A) falls (FIG. 17D). Accordingly, the switch SWL of theauxiliary driver unit 18 is turned on, electric charges move from thedrive electrode block B to the capacitive element CL via the line LAC,and the voltage of the drive electrode block B (FIG. 17G) falls for ashort time. Accordingly, the voltage Vcl of the capacitive element CLrises and maintains the level up to time t8 (to be described later)(FIG. 17F).

At time t4, the scanning control unit 51 of the drive electrode scanningunit 16 changes the Vcom selection signal VCOMSEL from a high level to alow level (FIG. 17B). Accordingly, in the driver unit 53 associated withthe touch detecting operation in the drive electrode scanning unit 16,the switch SW1 is turned off and the line LAC and the drive electrodeblock B are electrically isolated from each other.

Thereafter, in the period of times t6 to t11, the voltages of thecapacitive elements VH and VL are initialized using the pulse Pi of theAC drive signal VcomAC. Specifically, in the period of times t6 to t8,the drive signal generating unit 15 changes the AC drive signal VcomACto a high level (voltage VH) (FIG. 17A). At the same time, the controlunit 11 changes the control signal CTLH to a high level in apredetermined period started from time t6 and shorter than the pulsewidth of the pulse Pi (FIG. 17C). Accordingly, the switch SWH of theauxiliary driver unit 18 is turned on, the capacitive element CH ischarged via the line LAC by the drive signal generating unit 15, and thevoltage Vch of the capacitive element CH varies to the voltage VH.Thereafter, in a predetermined period started from time t8 in which theAC drive signal VcomAC is at a low level (0 V), the control unit 11changes the control signal CTLL to a high level (FIG. 17D). Accordingly,the switch SWL of the auxiliary driver unit 18 is turned on, thecapacitive element CL is discharged via the line LAC, and the voltageVcl of the capacitive element CL varies to 0 V.

In this way, in the display panel 1, since electric charges areexchanged between the capacitive element CH of the auxiliary driver unit18 and the drive electrodes COML belonging to the drive electrode blockB as a target of the touch detecting operation at the rising of thepulse Pt of the AC drive signal VcomAC, it is possible to shorten therising time tr of the voltage (the drive signal Vcom) of the driveelectrodes COML. Similarly, since electric charges are exchanged betweenthe capacitive element CL of the auxiliary driver unit 18 and the driveelectrodes COML at the falling of the pulse Pt, it is possible toshorten the falling time tf of the voltage (the drive signal Vcom) ofthe drive electrodes COML. Accordingly, for example, even when the drivesignal Vcom is supplied to the drive electrode block B separated fromthe drive signal generating unit 15 and located in the vicinity of theend of the line LAC, it is possible to shorten the transition time (therising time tr and the falling time tf) of the drive signal Vcom.

In this way, by shortening the transition time of the drive signal Vcom(pulse Pt), it is possible to reduce the possibility of lowering thetouch detection accuracy in the display panel 1. That is, for example,when the auxiliary driver unit 18 is not provided, the transition timeof the drive signal Vcom may increase and thus the pulse waveform maycollapse. In this case, since the collapsed pulse signal is transmittedto the touch detecting electrodes TDL and is output as the touchdetection signal Vdet, there is a possibility of lowering the touchdetection accuracy. On the contrary, in the display panel 1, since thetransition time of the drive signal Vcom (pulse Pt) can be shortened, itis possible to reduce the possibility of collapsing of the waveform ofthe drive signal Vcom and thus to reduce the possibility of lowering thetouch detection accuracy.

By shortening the transition time of the drive signal Vcom, it ispossible to cope with an increase in precision or an increase in size ofthe display panel 1 and the like. Specifically, for example, when ahigh-precision liquid crystal display device 20 is used, the ratio ofthe writing time of a pixel signal in a period of one frame increaseswith an increase in the number of horizontal lines and thus it isdifficult to guarantee the time for the touch detecting operation. Inthe display panel 1, since the transition time of the drive signal Vcomcan be shortened as described above, it is possible to shorten the timefor the touch detecting operation and to cope with an increase inprecision or an increase in size of the display panel 1.

The capacitance values of the capacitive elements CH and CL of theauxiliary driver unit 18 will be described below.

FIG. 18 shows the relationship between the capacitance values of thecapacitive elements CH and CL and the transition time (the rising timetr and the falling time tf) of the drive signal Vcom in the driveelectrode block B disposed in the vicinity of the end of the line LAC.In FIG. 18, the capacitance values of the capacitive elements CH and CLare expressed with the parasitic capacitance Cb of each drive electrodeblock B as a unit. That is, since the touch detection scanning isperformed in the display panel 1 by supplying the drive signal Vcom toeach drive electrode block B, the capacitance values of the capacitiveelements CH and CL are expressed with the parasitic capacitance Cb ofeach drive electrode block B as a unit.

As shown in FIG. 18, with an increase in capacitance values of thecapacitive elements CH and CL, the transition time of the drive signalVcom becomes shortened and the transition time is almost saturated whenthe capacitance values become about seven to ten times the parasiticcapacitance Cb. On the other hand, when the capacitance values of thecapacitive elements CH and CL increase, a larger arrangement area isnecessary. Accordingly, it is necessary to determine the capacitancevalues of the capacitive elements CH and CL in consideration of both thearrangement areas of the capacitive elements CH and CL and thetransition time. Specifically, in this example, it is preferable thatthe capacitance values of the capacitive elements CH and CL be set toabout three times the parasitic capacitance Cb.

[Advantages]

As described above, in this embodiment, since the auxiliary driver unitis disposed, it is possible to shorten the transition time of the drivesignal and thus to drive the respective drive electrode blocks for ashorter time.

In this embodiment, since the transition time of the drive signal isshortened, it is possible to reduce the possibility of collapsing of thewaveform of the drive signal and thus to suppress the lowering of thetouch detection accuracy.

In this embodiment, since the auxiliary driver unit is disposed at aposition separated from the drive signal generating unit, it is possibleto shorten the transition time of the drive signal in the driveelectrode separated from the drive signal generating unit.

In this embodiment, since the capacitive elements are initialized viathe line LAC, it is not necessary to provide a dedicated line forinitializing the capacitive elements and it is thus to possible toreduce the space for the line.

In this embodiment, since the capacitive elements are formed through theprocesses of manufacturing the display device with a touch detectingfunction, it is not necessary to add a manufacturing process and it isthus possible to simplify the manufacturing processes.

Modified Example 1-1

In the above-mentioned embodiment, the electrodes 61 of the capacitiveelements CH and CL are formed in the same layer as the pixel electrodes22 and the electrodes 62 are formed in the same layer as the driveelectrodes COML, but the embodiment of the present disclosure is notlimited to this configuration. For example, the electrodes may be formedas shown in FIGS. 19A and 19B. The capacitive element CH will bedescribed below as an example.

In the configuration shown in FIG. 19A, the capacitive element CHincludes electrodes 67 and 68 and an insulating layer 69 interposedbetween the electrodes 67 and 68. The electrode 67 is formed in the samelayer as the scanning signal line GCL (FIG. 7) and is formed of, forexample, aluminum. The electrode 68 is formed on the TFT substrate 21 inthe same layer as the gate electrode of the TFT element Tr and is formedof, for example, molybdenum. The electrode 67 is connected to aninterconnection layer 65 via plural contacts CONT2. In this example, theelectrode 67 (the interconnection layer 65) is connected to one end ofthe switch SWH and the electrode 68 is grounded. In the case of thecapacitive element CL, the electrode 67 (the interconnection layer 65)is connected to one end of the switch SWL and the electrode 68 isgrounded.

The configuration shown in FIG. 19B is obtained by combining theconfiguration (FIG. 14) according to the above-mentioned embodiment andthe configuration shown in FIG. 19A. That is, in this configuration, thecapacitor constructed by the electrodes 61 and 62 and the insulatinglayer 63 and the capacitor constructed by the electrodes 67 and 68 andthe insulating layer 69 are superimposed. In this example, theelectrodes 62 and 67 (the interconnection layer 65) are connected to oneend of the switch SWH and the electrodes 61 and 68 are grounded. In thecase of the capacitive element CL, the electrodes 62 and 67 (theinterconnection layer 65) are connected to one end of the switch SWL andthe electrodes 61 and 68 are grounded.

In this way, even when the capacitive elements CH and CL are constructedwith any configuration of FIGS. 19A and 19B, it is possible to form thecapacitive elements at the same time as forming the display device witha touch detecting function 10 without adding any manufacturing process.

Modified Example 1-2

In the above-mentioned embodiment, as shown in FIGS. 17A to 17G, thecontrol unit 11 changes the control signal CTLH from a low level to ahigh level at time t2 at which the AC drive signal VcomAC is changedfrom a low level to a high level and changes the control signal CTLLfrom a low level to a high level at time t3 at which the AC drive signalVcomAC is changed from a high level to a low level, but the embodimentof the present disclosure is not limited to this configuration.Alternatively, for example, as shown in FIGS. 20A to 20G, the controlsignal CTLH may be changed from a low level to a high level before timet2 and the control signal CTLL may be changed from a low level to a highlevel before time t3.

3. Second Embodiment

A display panel 7 according to a second embodiment of the presentdisclosure will be described below. In this embodiment, the capacitiveelements CH and CL of the auxiliary driver unit are initialized by theuse of a dedicated line. Substantially the same elements as in thedisplay panel 1 according to the first embodiment are referenced by thesame reference numerals and description thereof will not be repeated.

FIG. 21 shows a configuration example of the display panel 7 accordingto this embodiment. The display panel 7 includes a drive signalgenerating unit 75, an auxiliary driver unit 78, and a control unit 71.

The drive signal generating unit 75 generates a DC drive signal VcomDC,an AC drive signal VcomAC2, and DC signals Vchl and Vcl1. The AC drivesignal VcomAC2 is a signal including a pulse Pt with a low-level voltageof 0 V and a high-level voltage of VH. That is, the AC drive signalVcomAC2 is a signal including a pulse Pi unlike the AC drive signalVcomAC in the above-mentioned embodiment. The voltage of the DC signalVchl is a voltage VH in this example, and the voltage of the DC signalVcl1 is 0 V in this example. That is, in this example, the voltage ofthe DC signal Vchl is the same as the high-level voltage of the AC drivesignal VcomAC2 and the voltage of the DC signal Vcl1 is the same as thelow-level voltage of the AC drive signal VcomAC2. The drive signalgenerating unit 75 supplies the DC signal Vchl to the auxiliary driverunit 78 via a dedicated line LH and supplies the DC signal Vcl1 to theauxiliary driver unit 78 via a dedicated line LL.

The auxiliary driver unit 78 assists the driving operation of the drivesignal generating unit 75, similarly to the auxiliary driver unit 18 inthe first embodiment. At this time, the auxiliary driver unit 78initializes the capacitive elements CH and CL using the DC signals Vchland Vcl1 supplied from the drive signal generating unit 75 via the linesLH and LL. The control unit 71 supplies control signals CTL2 (CTLH2 andCTLL2) to the auxiliary driver unit 78.

FIG. 22 shows a configuration example of the auxiliary driver unit 78.In the auxiliary driver unit 78, one end of the capacitive element CH isconnected to one end of the switch SWH and is also connected to the lineLH. Similarly, one end of the capacitive element CL is connected to oneend of the switch SWL and is also connected to the line LL.

FIGS. 23A to 23G show timing waveform examples of a touch detectingoperation in the display panel 7, where FIG. 23A represents the waveformof the AC drive signal VcomAC2 in the output of the drive signalgenerating unit 75, FIG. 23B represents the waveform of the Vcomselection signal VCOMSEL, FIG. 23C represents the waveform of thecontrol signal CTLH2, FIG. 23D represents eh waveform of the controlsignal CTLL2, FIG. 23E represents the waveform of the voltage Vch of thecapacitive element CH, FIG. 23F represents the waveform of the voltageVcl of the capacitive element CL, and FIG. 23G represents the waveformof the drive signal Vcom supplied to the drive electrode block B as atarget of the touch detecting operation.

In the auxiliary driver unit 78, the capacitive element CH is normallysupplied with the DC signal Vchl (voltage VH) via the line LH and thecapacitive element CL is normally supplied with the DC signal Vcl1 (0 V)via the line LL. Accordingly, the voltage Vch of the capacitive elementCH is changed to the voltage VH when the control signal CTLH2 is changedfrom a high level to a low level and the switch SWH is turned off asshown in FIG. 23E, and the voltage Vcl of the capacitive element CL ischanged to 0 V when the control signal CTLL2 is changed from a highlevel to a low level and the switch SWL is turned off as shown in FIG.23F.

In this way, in the display panel 7, since the capacitive elements CHand CL are initialized by normally supplying the DC signals Vchl andVcl1 to the capacitive elements CH and CL, it is possible to simplifythe circuit operation. That is, in the first embodiment, the drivesignal generating unit 15 generates the pulse Pi and the auxiliarydriver unit 18 initializes the capacitive elements CH and CL on thebasis of the pulse Pi and the control signal CTL supplied from thecontrol unit 11. However, in this embodiment, since the capacitiveelements CH and CL are initialized on the basis of the DC signals Vchland Vcl1 normally supplied, it is possible to simplify the circuitoperation for initialization.

In this way, in this embodiment, since the DC signals are normallysupplied to the capacitive elements, it is possible to simplify thecircuit operation of initializing the capacitive elements. The otheradvantages are the same as in the first embodiment.

Modified Example 2-1

Modified Examples 1-1 and 1-2 of the first embodiment may be applied tothe display panel 7 according to the second embodiment.

Modified Example 2-2

Although it is stated in the above-mentioned embodiment that the voltageof the DC signal Vchl is set to be equal to the high-level voltage (thevoltage VH) of the AC drive signal VcomAC2 and the voltage of the DCsignal Vcl1 is set to be equal to the low-level voltage (0 V) of the ACdrive signal VcomAC2, the embodiment of the present disclosure is notlimited to this configuration and such voltages can be arbitrarily set.Specifically, For example, the voltage of the DC signal Vchl may be setto a voltage higher than the voltage VH and the voltage of the DC signalVcl1 may be set to a voltage lower than 0 V.

4. Third Embodiment

A display panel 8 according to a third embodiment will be describedbelow. In this embodiment, in the auxiliary driver unit 78 according tothe second embodiment, a switch is disposed between the line LH and thecapacitive element CH and a switch is disposed between the line LL andthe capacitive element CL similarly. Substantially the same elements asin the display panel 7 according to the second embodiment will bereferenced by the same reference numerals and description thereof willnot be repeated.

The display panel 8 includes an auxiliary driver unit 88 as shown inFIG. 21. In this example, the voltage of the DC signal Vchl generated bythe drive signal generating unit 75 is a voltage VH2 which is higherthan the voltage VH and the voltage of the DC signal Vcl1 is a voltageVL2 which is lower than 0 V.

FIG. 24 shows a configuration example of the auxiliary driver unit 88according to this embodiment. The auxiliary driver unit 88 includesinverters IVH and IVL and switches SWH2 and SWL2. The inverter IVHgenerates and outputs the inverted logic of a control signal CTLH2. TheON and OFF states of the switch SWH2 are controlled on the basis of theoutput signal of the inverter IVH, one end thereof is connected to oneend of the capacitive element CH, and the other end thereof is connectedto the line LH. The inverter IVL generates and outputs the invertedlogic of a control signal CTLL2. The ON and OFF states of the switchSWL2 are controlled on the basis of the output signal of the inverterIVL, one end thereof is connected to one end of the capacitive elementCL, and the other end thereof is connected to the line LL.

According to this configuration, in the auxiliary driver unit 88, oneend of the capacitive element CH is connected to the line LAC when thecontrol signal CTLH2 is at a high level, and is connected to the line LHwhen the control signal CTLH2 is at a low level. Similarly, one end ofthe capacitive element CL is connected to the line LAC when the controlsignal CTLL2 is at a high level, and is connected to the line LL whenthe control signal CTLL2 is at a low level.

Here, the switches SWH2 and SWL2 correspond to a specific example of the“voltage supply switch” in the embodiment of the present disclosure.

FIGS. 25A to 25G show timing waveform examples of a touch detectingoperation in the display panel 8, where FIG. 25A represents the waveformof the AC drive signal VcomAC2 in the output of the drive signalgenerating unit 75, FIG. 25B represents the waveform of the Vcomselection signal VCOMSEL, FIG. 25C represents the waveform of thecontrol signal CTLH2, FIG. 25D represents eh waveform of the controlsignal CTLL2, FIG. 25E represents the waveform of the voltage Vch of thecapacitive element CH, FIG. 25F represents the waveform of the voltageVcl of the capacitive element CL, and FIG. 25G represents the waveformof the drive signal Vcom supplied to the drive electrode block B as atarget of the touch detecting operation.

In the auxiliary driver unit 88, in the period in which the controlsignal CTLH2 is at a low level, the switch SWH2 is turned on and thevoltage Vch of the capacitive element CH is initialized to be a voltageVH2 (FIG. 25E). In the period in which the control signal CTLH2 is at ahigh level, similarly to the second embodiment or the like, the switchSWH is turned on and electric charges are exchanged between thecapacitive element CH and the drive electrode block B. Similarly, in theauxiliary driver unit 88, in the period in which the control signalCTLL2 is at a low level, the switch SWL2 is turned on and the voltageVcl of the capacitive element CL is initialized to be a voltage VL2(FIG. 25F). In the period in which the control signal CTLL2 is at a highlevel, the switch SWL is turned on and electric charges are exchangedbetween the capacitive element CL and the drive electrode block B. Thatis, when the control signals CTLH2 and CTLL2 are at a high level, thedisplay panel 8 operates so that the voltage (the drive signal Vcom) ofthe drive electrodes COML is changed for a short time by so-calledoverdrive.

In the display panel 8, in order to achieve the overdrive effect, thedrive signal generating unit 75 generates a voltage VH2 higher than thevoltage VH and supplies the generated voltage as the DC signal Vchl tothe auxiliary driver unit 88, and generates a voltage VL2 lower than 0 Vand supplies the generated voltage as the DC signal Vcl1 to theauxiliary driver unit 88. In the auxiliary driver unit 88, the switchesSWH and SWH2 work complementarily and the switches SWL and SWL2 workcomplementarily. Accordingly, in the display panel 8, since the line LACand the line LH are not directly connected to each other and the lineLAC and the line LL are not directly connected to each other, it ispossible to reduce the possibility in which the circuit operation isunstable.

As described above, in this embodiment, since the switch SWH2 working tobe complementary to the switch SWH is provided and the switch SWL2working to be complementary to the switch SWL is provided, it ispossible to reduce the possibility in which the circuit operation isunstable. The other advantages are the same as in the second embodiment.

Modified Example 3-1

Although it is described in the above-mentioned embodiment that thevoltage of the DC signal Vchl is set to a voltage VH2 higher than thevoltage VH and the voltage of the DC signal Vcl1 is set to a voltage VL2lower than 0 V, the embodiment of the present disclosure is not limitedto this configuration and, for example, the voltage of the DC signalVchl may be set to a voltage VH and the voltage of the DC signal Vcl1may be set to 0 V.

5. Application Examples

Application examples of the display panel described in theabove-mentioned embodiments and modified examples will be describedbelow.

FIG. 26 shows the appearance of a television set to which the displaypanel according to the above-mentioned embodiments is applied. Thetelevision set includes, for example, includes an image display screenunit 510 including a front panel 511 and a filter glass 512. The imagedisplay screen unit 510 is constructed by the display panel according tothe above-mentioned embodiments or the like.

The display panel according to the above-mentioned embodiments or thelike can be applied to electronic apparatuses in all the fields such asportable terminals such as a digital camera, a notebook personalcomputer, and a mobile phone, portable game machines, and video cameras,in addition to the television set. In other words, the display panelaccording to the above-mentioned embodiments or the like can be appliedto electronic apparatuses of all the fields displaying an image.

Although the present disclosure is described above with reference toseveral embodiments, modified examples thereof, and application examplesof the electronic apparatus, the present disclosure is not limited tothe embodiments and the like and can be modified in various forms.

For example, in the above-mentioned embodiments and the like, theconfiguration of the capacitive element CH and the configuration of thecapacitive element CL in each auxiliary driver unit 18, 78, or 88 areset to be equal to each other, but the present disclosure is not limitedto this configuration. An example thereof will be described below indetail.

FIG. 27 shows a configuration example of a display panel 7B according tothis modified example. The display panel 7B includes a drive signalgenerating unit 75B, an auxiliary driver unit 78B, and a control unit71B. The drive signal generating unit 75B generates a DC drive signalVcomDC, and AC drive signal VcomAC2, and a DC signal Vchl. That is, thedrive signal generating unit 75B does not generate the voltage Vcl1,unlike the drive signal generating unit 75 according to the secondembodiment. Similarly to the auxiliary driver unit 78 according to thesecond embodiment, the auxiliary driver unit 78B assists the drivingoperation of the drive signal generating unit 75B. At this time, theauxiliary driver unit 78B initializes the capacitive element CH usingthe DC signal Vchl supplied from the drive signal generating unit 75B.The control unit 71B supplies control signals CTLH2 and CTLL to theauxiliary driver unit 78B.

FIG. 28 shows a configuration example of the auxiliary driver unit 78B.In the auxiliary driver unit 78B, one end of the capacitive element CHis connected to one end of the switch SWH and is also connected to theline LH. On the other hand, one end of the capacitive element CL isconnected to only one end of the switch SWL. That is, in the auxiliarydriver unit 78B, the configuration of the capacitive element CH isdifferent from the configuration of the capacitive element CL.Specifically, the auxiliary driver unit 78B combines the configuration(FIG. 22) of the capacitive element CH in the auxiliary driver unit 78according to the second embodiment and the configuration (FIG. 13) ofthe capacitive element CL in the auxiliary driver unit 18.

FIGS. 29A to 29G show a timing waveform example of a touch detectingoperation in the display panel according to this modified example, whereFIG. 29A represents the waveform of the AC drive signal VcomAC2 in theoutput of the drive signal generating unit 75B, FIG. 29B represents thewaveform of the Vcom selection signal VCOMSEL, FIG. 29C represents thewaveform of the control signal CTLH2, FIG. 29D represents eh waveform ofthe control signal CTLL2, FIG. 29E represents the waveform of thevoltage Vch of the capacitive element CH, FIG. 29F represents thewaveform of the voltage Vcl of the capacitive element CL, and FIG. 29Grepresents the waveform of the drive signal Vcom supplied to the driveelectrode block B as a target of the touch detecting operation. In theauxiliary driver unit 78B, the capacitive element CH is initialized bybeing normally supplied with the DC signal Vchl (the voltage VH) via theline LH, similarly to the auxiliary driver unit 78 according to thesecond embodiment, and the capacitive element CL is initialized by beingsupplied with 0 V via the line LAC in a predetermined period startedfrom time t8, similarly to the auxiliary driver unit 18 according to thefirst embodiment.

By employing this configuration, it is possible to reduce the space forthe line LL, compared with the display panel 7 according to the secondembodiment, and it is possible to simplify the circuit operation ofinitializing the capacitive elements CH and CL, compared with thedisplay panel 1 according to the first embodiment.

For example, in the above-mentioned embodiments and the like, as shownin FIG. 6, the drive electrodes COML are formed on the TFT substrate 21and the pixel electrodes 22 are formed thereon with the insulating layer23 interposed therebetween, but the present disclosure is not limited tothis configuration. For example, the pixel electrode 22 may be formed onthe TFT substrate 21 and the drive electrodes COML may be formed thereonwith the insulating layer 23 interposed therebetween.

For example, in the above-mentioned embodiments and the like, the liquidcrystal display device using liquid crystal of a transverse electricfield mode such as FFS or IPS and the touch detecting device areincorporated into a body. However, a liquid crystal display device usingliquid crystal of various modes such as TN (Twisted Nematic), VA(Vertically Aligned), and ECB (Electric field Controlled Birefringence)and a touch detecting device may be incorporated into a body. When suchliquid crystal is used, the display device with a touch detectingfunction can be constructed as shown in FIG. 30. FIG. 35 shows anexample of a partial sectional structure of a display device with atouch detecting function 10D according to this modified example andshows a state where a liquid crystal layer 6B is interposed between apixel substrate 2B and a counter substrate 3B. Names or functions of theother elements are the same as shown in FIG. 6 and description thereofwill not be repeated. In this example, unlike the configuration shown inFIG. 6, the drive electrodes COML used both for display and for touchdetection are formed on the counter substrate 3B.

For example, in the above-mentioned embodiments, the liquid crystaldisplay device and the capacitance type touch detecting device areincorporated into a body to construct a so-called in-cell type, but thepresent disclosure is not limited to this configuration. For example, aso-called on-cell type may be employed in which a capacitance type touchdetecting device is formed on the surface of a liquid crystal displaydevice. In the on-cell type, for example, when noise of a displaydriving operation propagates from the liquid crystal display device tothe touch detecting device, the noise can be reduced by driving thedisplay panel as described in the above-mentioned embodiments, and it isthus possible to suppress the lowering of the touch detection accuracy.

For example, in the above-mentioned embodiments, the display deviceemploys the liquid crystal device, but the present disclosure is notlimited to this configuration. For example, EL (Electroluminescence)device may be employed.

The present disclosure may be implemented as the followingconfigurations.

(1) A display panel including: display elements; a plurality of driveelectrodes; one or more touch detecting electrodes that form a capacitoralong with the corresponding drive electrode; a main driver unit thatgenerates a basic drive signal including a pulse part supplied to thedrive electrodes; and a first auxiliary driver unit that includes acapacitive element and that exchanges electric charges between thecapacitive element and the drive electrodes in synchronization with thepulse part.

(2) The display panel according to (1), wherein the first auxiliarydriver unit further includes a first switch that controls the exchangeof electric charges between the capacitive element and the driveelectrode, wherein the pulse part changes between two voltage levels,and wherein the first switch is turned on at the time corresponding tothe rising or falling of the pulse part.

(3) The display panel according to (2), wherein the pulse part changesfrom a voltage of a first level to a voltage of a second level, andwherein the capacitive element is set to a voltage of a third levelpreviously determined depending on the voltage of the second level in aperiod in which the first switch is turned off.

(4) The display panel according to (3), wherein the basic drive signalincludes a DC part which is maintained at the voltage of the third levelin a period other than the period in which the pulse part appears, andwherein the first switch is also turned on in the period in which the DCpart appears in the basic drive signal.

(5) The display panel according to (3), further including a voltagesupply unit that generates and supplies the voltage of the third levelto the capacitive element.

(6) The display panel according to (3), further including a voltagegenerating unit that generates the voltage of the third level, whereinthe first auxiliary driver unit further includes a voltage supply switchthat controls the supply of the voltage of the third level, which isgenerated by the voltage generating unit, to the capacitive element.

(7) The display panel according to (6), wherein the voltage supplyswitch is turned on in a period in which the first switch is turned off.

(8) The display panel according to any one of (3) to (7), wherein thevoltage of the third level is at the same voltage level as the voltageof the second level.

(9) The display panel according to any one of (3) to (7), wherein thevoltage of the third level is higher than the voltage of the secondlevel when the voltage of the second level is higher than the voltage ofthe first level, and is lower than the voltage of the second level whenthe voltage of the second level is lower than the voltage of the firstlevel.

(10) The display panel according to any one of (2) to (9), wherein thefirst switch is turned on at the same time as or just before the risingof the pulse part or at the same time as or just before the falling ofthe pulse part.

(11) The display panel according to any one of (1) to (10), wherein theplurality of drive electrodes are formed to extend in a predetermineddirection and are arranged to be perpendicular to the predetermineddirection, wherein the main driver unit is disposed in the vicinity ofthe drive electrode which is disposed at one end of each of theplurality of drive electrodes, and wherein the first auxiliary driveunit is disposed in the vicinity of the drive electrode which isdisposed at the other end thereof.

(12) The display panel according to any one of (1) to (11), furtherincluding a scanning unit that supplies the pulse part of the basicdrive signal to the plurality of drive electrodes at every predeterminednumber of drive electrodes, wherein the capacitance value of thecapacitive element is less than or equal to ten times the capacitancevalue of the predetermined number of drive electrodes.

(13) The display panel according to any one of (1) to (12), furtherincluding a second auxiliary driver unit that includes a capacitiveelement and a second switch controlling exchange of electric chargesbetween the capacitive element and the drive electrodes, wherein thesecond switch is turned on at the time other than the time at which thefirst switch is turned on out of the rising time and the falling time ofthe pulse part.

(14) The display panel according to any one of (1) to (13), wherein eachdisplay element includes a liquid crystal layer, and a pixel electrodethat is formed between the liquid crystal layer and the correspondingdrive electrode or is formed to face the liquid crystal layer with thecorresponding drive electrode interposed therebetween.

(15) The display panel according to (14), wherein the capacitive elementincludes an electrode formed in the same layer as the drive electrodesand an electrode formed in the same layer as the pixel electrodes.

(16) The display panel according to (14) or (15), wherein each displayelement further includes a pixel transistor, and wherein the capacitiveelement includes an electrode formed in the same layer as the gateelectrode of the pixel transistor.

(17) The display panel according to any one of (1) to (13), wherein eachdisplay element includes a liquid crystal layer, and a pixel electrodethat is disposed to face the corresponding drive electrode with theliquid crystal layer interposed therebetween.

(18) A driver circuit including a capacitive element, wherein electriccharges are exchanged between the capacitive element and a driveelectrode in synchronization with a pulse part, which is supplied to thedrive electrode, of a basic drive signal.

(19) A driving method of supplying a pulse part of a basic drive signalto a drive electrode and exchanging electric charges between acapacitive element and the drive electrode in synchronization with thepulse part.

(20) An electronic apparatus including: a display panel; and a controlunit that controls an operation of the display panel, wherein thedisplay panel includes display elements, a plurality of driveelectrodes, one or more touch detecting electrodes that form a capacitoralong with the corresponding drive electrode, a main driver unit thatgenerates a basic drive signal including a pulse part supplied to thedrive electrodes, and a first auxiliary driver unit that includes acapacitive element and that exchanges electric charges between thecapacitive element and the drive electrodes in synchronization with thepulse part.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

1. A display panel comprising: display elements; a plurality of driveelectrodes; one or more touch detecting electrodes that form a capacitoralong with the corresponding drive electrode; a main driver unit thatgenerates a basic drive signal including a pulse part supplied to thedrive electrodes; a first auxiliary driver unit that includes acapacitive element and that exchanges electric charges between thecapacitive element and the drive electrodes in synchronization with thepulse part; and a voltage supply unit, wherein the first auxiliarydriver unit further includes a first switch that controls the exchangeof electric charges between the capacitive element and the driveelectrode, wherein the pulse part changes between two voltage levels,wherein the first switch is turned on at the time corresponding to therising or falling of the pulse part, wherein the pulse part changes froma voltage of a first level to a voltage of a second level, wherein thecapacitive element is set, in a period in which the first switch isturned off, to a voltage of a third level that is previously determineddepending on the voltage of the second level, and wherein the voltagesupply unit generates and supplies the voltage of the third level to thecapacitive element.
 2. The display panel according to claim 1, whereinthe first auxiliary driver unit further includes a voltage supply switchthat controls the supply of the voltage of the third level, which isgenerated by the voltage supply unit, to the capacitive element.
 3. Thedisplay panel according to claim 2, wherein the voltage supply switch isturned on in a period in which the first switch is turned off.
 4. Thedisplay panel according to claim 1, wherein the voltage of the thirdlevel is at the same voltage level as the voltage of the second level.5. The display panel according to claim 1, wherein the voltage of thethird level is higher than the voltage of the second level when thevoltage of the second level is higher than the voltage of the firstlevel, and is lower than the voltage of the second level when thevoltage of the second level is lower than the voltage of the firstlevel.
 6. The display panel according to claim 1, wherein the firstswitch is turned on at the same time as or just before the rising of thepulse part or at the same time as or just before the falling of thepulse part.
 7. The display panel according to claim 1, wherein each ofthe drive electrodes extends in a predetermined direction, and the driveelectrodes are arranged in a direction perpendicular to thepredetermined direction, wherein the main driver unit is disposed in avicinity of the drive electrode which is disposed at one end of each ofthe plurality of drive electrodes, and wherein the first auxiliary driveunit is disposed in the vicinity of the drive electrode which isdisposed at the other end thereof.
 8. The display panel according toclaim 1, further comprising a scanning unit that supplies the pulse partof the basic drive signal to the plurality of drive electrodes at everypredetermined number of drive electrodes in a drive electrode block,wherein the capacitance value of the capacitive element is less than orequal to ten times the capacitance value of a parasitic capacitancebetween the predetermined number of drive electrodes in the driveelectrode block.
 9. The display panel according to claim 1, furthercomprising a second auxiliary driver unit that includes a capacitiveelement and a second switch controlling exchange of electric chargesbetween the capacitive element and the drive electrodes, wherein thesecond switch is turned on at the time other than the time at which thefirst switch is turned on out of the rising time and the falling time ofthe pulse part.
 10. The display panel according to claim 1, wherein eachdisplay element includes a liquid crystal layer, and a pixel electrodethat is formed between the liquid crystal layer and the correspondingdrive electrode or is formed to face the liquid crystal layer with thecorresponding drive electrode interposed therebetween.
 11. The displaypanel according to claim 10, wherein the capacitive element includes anelectrode formed in the same layer as the drive electrodes and anelectrode formed in the same layer as the pixel electrodes.
 12. Thedisplay panel according to claim 10, wherein each display elementfurther includes a pixel transistor, and wherein the capacitive elementincludes an electrode formed in the same layer as the gate electrode ofthe pixel transistor.
 13. The display panel according to claim 1,wherein each display element includes a liquid crystal layer, and apixel electrode that is disposed to face the corresponding driveelectrode with the liquid crystal layer interposed therebetween.
 14. Anelectronic apparatus comprising: a display panel; and a control unitthat controls an operation of the display panel, wherein the displaypanel includes display elements, a plurality of drive electrodes, one ormore touch detecting electrodes that form a capacitor along with thecorresponding drive electrode, a main driver unit that generates a basicdrive signal including a pulse part supplied to the drive electrodes, afirst auxiliary driver unit that includes a capacitive element and thatexchanges electric charges between the capacitive element and the driveelectrodes in synchronization with the pulse part, and a voltage supplyunit, wherein the first auxiliary driver unit further includes a firstswitch that controls the exchange of electric charges between thecapacitive element and the drive electrode, wherein the pulse partchanges between two voltage levels, wherein the first switch is turnedon at the time corresponding to the rising or falling of the pulse part,wherein the pulse part changes from a voltage of a first level to avoltage of a second level, wherein the capacitive element is set, in aperiod in which the first switch is turned off, to a voltage of a thirdlevel that is previously determined depending on the voltage of thesecond level, and wherein the voltage supply unit generates and suppliesthe voltage of the third level to the capacitive element.